Evaluation of Cold Resistance and Semi-lethal Low Temperature(LT_(50))of Nine Pear Cultivars

[Objectives]To evaluate the cold resistance and semi-lethal temperature of pear cultivars,and provide a theoretical basis for the regional extension and breeding of cold-resistant pear cultivars.[Methods]Nine pear cultivars were used to study the changes in relative conductivity and cell injury rate of pear branches under low temperature stress,and the semi-lethal temperature(LT_(50))of pear branches was analyzed by fitting Logistic equation.[Results]The relative conductivity and cell injury rate of pear branches took on the trend of slow increase,rapid increase,and slow increase the decrease of treatment temperature.The LC_(50) of the nine pear cultivars were as follows:Nanguo pear-33.9℃,Wanyu-32.3℃,Red D Anjou-31.8℃,Jinfeng-31.3℃,Wujiuxiang-29.2℃,20 th Century Pear-29.1℃,Hanxiang-35.1℃,Yuluxiang-27.9℃ and Korla Fragrant Pear-29.2℃.[Conclusions]The semi-lethal temperature could reflect the cold resistance of pear trees,and Wanxiang had better cold resistance.The evaluation of cold resistance and semi-lethal temperature of pear cultivars can provide theoretical basis for regional extension and breeding of cold-resistant pear cultivars.

Advances in Molecular Regulatory Mechanisms of Fruit Trees under Low Temperature Stress

The most recent research findings on the tolerance of fruit trees to cold stress are reviewed from a molecular perspective,including the perception and transduction of low temperature calcium signaling,CBF-dependent molecular regulatory mechanisms,non-CBF-dependent molecular regulatory mechanisms,and so forth.The objective is to provide a reference basis for further improving the cold resistance of fruit trees and cultivating new varieties of hardy plants.

A Light and Simplified Branch Bending Method for Young Pear Trees

Aiming at high cost and low efficiency of conventional branch bending method in the modern intensive planting and labor-saving cultivation mode of young pear trees,this paper provides a new branch bending method with wide source of raw materials,cheap price and simple operation,which is also suitable for the management of low-age branches in the process of high grafting and upgrading of traditional big trees.

A method for Improving the Efficiency of Pear Tree Crossbreeding

In view of the short blooming period of pear tree crossbreeding and the complexity of pollination process, a method that can improve the efficiency of crossbreeding of pear trees was provided. Meanwhile, this method can also be applied to the study of pollen xenia effect, pollination tree selection and pure pollen collection in pear tree cultivation.

Occurrence and Integrated Control of Psylla chinensis in Eastern Hebei Province

The paper introduces the damage characteristics and occurrence regularity of Psylla chinensis in pear orchards in eastern Hebei Province,and summarizes the integrated prevention and control techniques of P.chinensis,in order to provide a reference for the prevention and control of P.chinensis in eastern Hebei Province.

Study on the Changes of the Major Nutrient Elements During Simple Composting Process of Dry Chicken Manure

[Objectives]This study was conducted to provide a theoretical basis for production and application of chicken manure compost.[Methods]With dry manure as a material,the variations of the major nutrients during simple composting process of dry chicken manure were studied,in order to get the best fermentation method.[Results]Chicken manure should not be preserved wet,but should be preserved after air-drying and fermented before use.Necessary moisture,simple sealing treatment and a certain amount of N element were conducive to simple fermentation of chicken manure.The treatments in which the chicken manure was wrapped around and compacted,added with an appropriate amount of water(50%-60%)and naturally fermented,or was wrapped around and compacted and added with an appropriate amount of water(50%-60%)and 0.2%of urea,were more appropriate for the production directly.[Conclusions]This study provides a theoretical basis for the actual production and application of chicken manure compost.

Optimization of Texture Determination of ‘Yali' by Texture Analyzer

[Objectives] This study was carried out to determine texture parameters for texture profile analysis （TPA）, and optimize the texture determination of ‘Yali’ by texture analyzer.[Methods] The traditional varieties of ‘Yali’ were taken as the materials, and texture parameters were determined at different compression rates and deformations at target.[Results] In the process of the TPA, the deformation at target had an extremely significant influence on 8 TPA texture parameters, namely, the hardness, cohesiveness, springiness, adhesiveness, gumminess, resilience, fracturability, and chewiness （ P ≤0.01）, while the compression rate had significant influence on the hardness and gumminess （ P ≤0.05）, had an extremely significant influence on fracturability （ P ≤0.01）, and had no significant influence on other 5 TPA parameters.[Conclusions] Taking the compression rate of 1 mm/s and 20% deformation at target as the experimental conditions for TPA could avoid the impact load of high speed on the tissue and objectively reflect the textural characteristics of ‘Yali’ pulp tissue.

Construction of Technology System on Development and Repropagation in Vitro of Several Cultivars in Pear

It is the most available way to obtain self-rooted seedlings by tissue culture,which could breed de-virus seedlings with uniform traits and contribute to improve seedling quality.To construct a complete and efficient technology system,this test used stem with buds of 16 cultivars and super lines including Yali,Jingbaili,03-04-034,03-08-080 and so on as materials to study the best way for explant sampling time and position,sterilization time using HgCl 2 and hormone concentrations.The result indicated that the optimum technology system was that the middle parts of longest shoots before 20 d after full-blossom were sterilized for 8 min by 0.1%HgCl 2 and inoculated on the development medium MS+6-BA 0.5 mg/L+IBA 0.2 mg/L+saccharose 3%+agar 0.6%(pH=5.8),and then trans-inoculated into propagation medium MS+6-BA 1.0 mg/L+IBA 0.3 mg/L+saccharose 3%+agar 0.6%(pH=5.8).

Differential Gene Expression and Analysis inVenturia nashicola-inoculated and UninoculatedLeaves of the New Highly Resistant Germplasm03-04-034

The super line 03-04-034, which results from a cross between Pyrus bretchneideri cv Jingbaili and P.ussuriensis cv Yali, is highly resistant to pear scab.Specimens were inoculated with Venturia nashicola to generate a database of expressed sequence tags(ESTs) to be used as resources for transcripts induced in inoculated and uninoculated leaves. After performing subtractive suppression hybridization using cDNA of the inoculated and uninoculated leaves harvested 51 h after inoculation, 100 clones from the uninoculated and 100 clones from the inoculated cDNA library were selected and sequenced. BLASTN searches of each cDNA library against GenBank revealed eight unique sequences associated with the defense response, comprising four ESTs from the uninoculated cDNA library(ubiquitin extension protein, subtilisin-like protease, basic helix-loop-helix(bHLH) transcription factor and aspartic endopeptidase) and four ESTs from the inoculated cDNA library(S-adenosylmethionine synthase(SAMS), heat shock factor(HSF) domain class transcription factor, RNA-binding protein and polyphenol oxidase 5 precursor).Quantitative fluorescence real-time polymerase chain analysis revealed that the transcripts for SAMS and subtilisin-like protease were highly expressed in the incompatible interaction. The SAMS gene was more highly expressed in inoculated leaves than uninoculated leaves, while the reverse was true for subtilisin-like protease. The SAMS and subtilisin-like protease genes have been found to be associated with plant defense mechanisms. Further studies of greater detail are required to understand how these genes are expressed and regulated during infection with V.nashicola.

Occurrence and Control of Pear Rust in Eastern Hebei Province

In recent years, pear rust sometimes occurs in eastern Hebei area, resulting in early defoliation, fruit abscission and loss of fruit commodity value. In this paper, the incidence symptoms, regularity and causes of pear rust are summarized, and the comprehensive prevention and control measures of pear rust in eastern Hebei are put forward.

A Training System of Pear Trees for Simplified High-density Cultivation

In view of the deficiencies of training technologies during constructing pear orchards by modern simplified dense-planting cultivation with ordinary pear seedlings widely used in production,a simple and easy-to-operate training method was proposed,mainly including constructing fence nets,determining low main trunks,leaving buds at the northwest position,multiple bud removal,winding and notching,simplified branch supporting,and simplified branch pulling.

Key Points of Prevention and Control Technology against Pear Powdery Mildew

Due to the lack of attention to the prevention and control of powdery mildew in pear orchard in autumn,the occurrence of pear powdery mildew is aggravating year by year,and it has become one of the main diseases of pear tree.In this paper,the symptom diagnosis,incidence regu-larity and prevention and control technology of pear powdery mildew are summarized,which will provide the reference for prevention and treatment of pear powdery mildew in production.